The physical structures of various materials (e.g., organic, inorganic and/or biologic) are vital for determining, for example, physical properties (e.g., functionality, size, physical properties, electrical properties, mechanical properties, dielectric properties, thermal properties, etc.) of various materials (e.g., solids, liquids, gasses and/or plasmas). In this regard, certain materials may have similar chemical compositions, but very different physical properties due to, for example: (1) different arrangements of ions, atoms, molecules and/or macromolecules of various sizes and/or shapes; (2) different bonding angles between atoms, ions, molecules and/or macromolecules; and/or (3) different types of bonds holding together ions, atoms, molecules and/or macromolecules, etc. The prior art refers generally to the formation and/or control of structures in the areas of biology, inorganic chemistry and/or organic chemistry as crystal growth, crystallization, crystal engineering and/or structural or phase engineering of materials.
Crystal growth or crystallization begins with, for example, primary nucleation, followed by secondary nucleation. However, in crystal systems that do not appear to require primary nucleation (e.g., some type of seed is typically provided) then only secondary nucleation may occur.
There are numerous crystallization models postulated in the prior art which attempt to explain crystallization reactions in certain material systems. These models include: (1) the broken band model which focuses on the energy of dissociated atoms being proportional to the number of bonds between nearest neighbors; (2) the free energy model which focuses on the free energies associated with various structural configurations in lattices; (3) the step-step interactions which focus on dipole-dipole interactions; (4) Wulff's construction, which focuses on minimization of surface free energies to obtain crystalline shapes; (5) Frank's model which theorizes that the velocity of growth or dissolution depends on surface orientation; (6) the BCF (Burton, Cabrera, Frank) model which focuses on step flow or a series of growth stages occurring due to the presence of a series of steps or ledges; (7) the Schwoebel Effect which discusses adatoms overcoming a potential energy maximum prior to adhering; and (8) various other crystallization models which take into account, for example, impurities, electric field effects, liquid field theory and/or morphology, etc. None of the various proposed models or theories for crystal growth explain satisfactorily the relevant mechanisms of crystal growth. Accordingly, detailed control of crystal growth or crystallization in many different areas of science remains an empirical science with numerous trials and errors often occurring to achieve desirable crystalline growth or engineering and/or desirable phases, structures or phase transformations.
It is well known that certain ions or atoms have an affinity for other atoms and/or ions, and thus, may be capable of bonding to each other by the well-known techniques of ionic bonding, covalent bonding, polar-covalent bonding, metallic bonding, hydrogen bonding, Van der Waal forces, etc., and/or hybrids or combinations of the same. The particular types of bonds which hold together atoms, ions, molecules and/or macromolecules, influence, for example, the positioning of ions, atoms, molecules and/or macromolecules, relative to each other (e.g., including such factors as separation, distances, bond angles, coordination number, etc.). Moreover, molecules (e.g., combinations of atoms) can be bonded to other molecules or molecular ions (e.g., proteins composed of molecules of amino acids) and also exhibit various spacings and angular displacements relative to each other. Still further, there are certain materials that have mixtures of atoms and molecules, whereby the atoms and molecules are bonded together by more than one of the bonding techniques mentioned above, and are also thereby located at certain distances and angles with respect to each other. Further, there are numerous macromolecules (e.g., viruses which are composed of different proteins, water, etc.) that contain various structural and angular relationships between different molecules of the same (or substantially the same) chemical composition.
One of the most basic structures that is used to refer structurally to arrangements of atoms, ions, molecules, etc., is the unit cell. For example, the unit cells of seven (7) different crystal systems are shown in FIG. 70. In particular, FIG. 70a shows a cubic unit cell structure; FIG. 70b shows a tetragonal unit cell structure; FIG. 70c shows an orthorhombic unit cell structure; FIG. 70d shows a monoclinic unit cell structure; FIG. 70e shows a triclinic unit cell structure; FIG. 70f shows a rhombohedral unit cell structure; and FIG. 70g shows a hexagonal unit cell structure. Moreover, Table A shows relationships between the various unit cell dimensions and angles shown in FIG. 70 as well as certain examples of certain inorganic materials which exhibit the aforementioned unit cell structures.
TABLE AUnit Cell DimensionsCrystal ClassExamplea = b = c a = β = γ = 90°CubicNaCl, MgAl2O4,C60K3a = b ≠ c a = β = γ = 90°TetragonalK2NiF4, TiO2,BaTiO3 (298K)a ≠ b ≠ c a = β = γ = 90°OrthorhombicYBa2, Cu3, O7a ≠ b ≠ c a = γ = 90° β ≠ 90°MonoclincKH2PO4a ≠ b ≠ c a ≠ β ≠ γ ≠ 90°Triclinica = b ≠ c a = β = 90° γ = 120°HexagonalLiNbO3a = b = c a = β = γ ≠ 90°Trigonal/BaTiO3 belowRhombohedral(−80° C.)
Various known inorganic, biologic and/or organic atoms, ions, molecules and/or macromolecules may adopt one or more of the unit cell arrangements shown in FIGS. 70a-70g. There are various known rules and experimental determinations that assist in predicting the various unit cells and/or macrostructures which may result from combinations of various ions, atoms, molecules and/or macromolecules of similar or different chemical compositions. For example, with specific reference to inorganic systems, different types of bonds that can be used to bond species together include covalent bonding, ionic bonding, Van der Waals bonding, metallic bonding, etc. For example, in covalently bonded crystals, the covalency of the atom(s) or ion(s) and the characteristics of the spatial distribution of the bonds in which the atoms form are the primary factors for determining the coordination or bonding or the particular assembly of atoms or ions in a structure.
In contrast, electrostatic bonding or ionic bonding is governed by several different rules. Specifically:
(1) The first rule, as an approximation, treats ions as rigid spheres and the way in which the spherical ions are packed together is determined by the relative sizes of the ions. In particular, a coordinated polyhedron of anions is formed around each cation, the cation-anion distance being determined by the radius sum and the coordination number of the cation by the radius ratio.
(2) The second rule is known as the electrostatic valency principle. This rule causes a charge balancing to occur. In particular, in a stable coordinated structure, the total strength of the valency bonds which reach an anion from all neighboring cations is equal to the charge of the anion. This rule causes structures to assume configurations of minimum potential energies in which the ions try to achieve electrical neutrality in their locality (e.g., in their unit cells).
(3) The third rule references the existence of edges and faces which may be common to two anion polyhedra in a coordinated structure. In particular, stabilities of polyhedra are decreased by the existence of edges and faces. This effect can be large for cations with high valency and small coordination numbers, and can be especially large when the radius ratio approaches the lower limit of stability of the polyhedron. This rule is due to the fact that an edge, or a face, which is common to two anion and polyhedra, will result in the close approach of two cations, and a corresponding increase in the potential energy of the system as compared with a state in which only corners are shared and thus, the cations are spaced apart as far as possible.
(4) The fourth rule is that in crystals containing different cations, those of high valency and small coordination number typically do not share polyhedron elements with each other. This rule follows the third rule stated above.
(5) The final general rule is that the number of different kinds of constituents in a crystal tends to be small in number.
The five aforementioned general rules also have certain applicability in organic and biologic systems, but have been specifically referenced with regard to inorganic systems to simplify the discussion thereof.
By following each of the aforementioned rules, different crystalline structures (or phases or patterns) may be obtainable in similar (or exactly the same) chemical systems. This aspect of obtaining different crystalline structures but having the same (or substantially the same) chemical structure is known as polymorphism. A substance is typically referred to as being polymorphous when it is capable of existing in two or more forms having different crystalline structures or patterns. Examples of well-known polymorphs include, carbon, selenium, quartz (SiO2), certain metals, barium titanate, zinc sulfide, ferric oxide, silica, proteins, prions, lipids, hydrocarbons, glycine, etc. In certain polymorphs, a first crystalline form can be found under a first set of physical conditions and a reversible transition may exist between different forms, said reversible transition being capable of occurring by, for example, one or more changes in certain of the physical conditions (e.g., environmental conditions to which the polymorphs are exposed) or by introduction of a catalyst. These types of materials are said to be enantiotropic. When transitions between crystalline forms or states is irreversible, the forms are said to be monotropic. An example of an enantiomer is iron which has a cubic packed structure between the temperatures of about 906° C.-1401° C., and a cubic body-centered structure with temperatures outside this range. Water also exhibits different structural forms (e.g., microclusters, macroclusters, etc.) and there are at least 13 different crystalline H2O structures that are known to exist in relatively modest pressure and temperature regimes. A third example are certain proteins, which when exposed to a polymorphic prion, change structure to match that of the prion via an autocatalytic transition.
There are various rules that assist in identifying relationships that exist between polymorphous forms of different substances. Specifically, the prior art has attempted to classify polymorphic changes into the following areas. For example, the recognized polymorphs that exist include one or more of the following relationships:
(1) changes in which the immediate coordination number of the ions/atoms is not significantly altered;
(2) changes in which a change in immediate coordination occurs;
(3) changes involving a transition between an ideal structure and a defect structure; and
(4) changes in which a change in bond-type occurs.
Each of the four (4) aforementioned polymorph relationships may be mutually exclusive, or may contain features of the other. However, it should be understood that various different configurations, such as unit cell, protein folding, or DNA twisting, exist for a large number of materials of substantially similar composition or compositions which are substantially identical.
In addition to the unit cells shown in FIGS. 70a-70g, there are different lattices available for use in combination with the unit cells. In particular, a lattice is known as an array of equivalent points in one, two, or more typically, three dimensions. Lattices typically do not provide any information regarding the actual positions of atoms or molecules in any particular spatial relationship, but show the various translational symmetries of the various atoms, ions or molecules by locating equivalent positions within the lattice. The environment of any atom or ion placed on one of the lattice points will be identical to the environment of a similar atom or ion placed on a corresponding different lattice point. The simplest illustration of this concept is a one-dimensional lattice consisting of an infinite series of equally spaced points along a line (see, for example, FIG. 71). However, the more realistic uses of lattices occurs in three-dimensional crystal structures. The simplest lattice type is known as a primitive (represented by the symbol “P”), and a unit cell with a primitive lattice contains a single lattice point.
A second lattice-type is body-centered (represented by the symbol “I”). FIG. 72 shows a body-centered cubic structure.
A lattice which has lattice points at the center of all unit faces as well as at the corners is known as a face-centered lattice and is represented by the symbol “F”. This lattice is shown in FIG. 73.
A final lattice which contains points in just one of the faces is known as face-centered, but can be given any one of the symbols “A”, “B” or “C”. A “C-type” lattice refers to the situation where additional translational symmetry places lattice points at the centers of the faces; whereas the A and B face-centered lattices are obtained in an identical manner but the additional lattice points occur in different planes. An example of a face-centered lattice is given in FIG. 74. It is noted that the “A” and “B” face-centered lattices are obtained in identical manner but the additional lattice points in the be and ac planes respectively are obtained. Accordingly, face-centered cubic lattice structures are typically referred to by the letter “C”.
The four different lattice types discussed above (i.e., P, I, F and C) can be combined with the seven unit cell or crystal classes which gives rise to all possible variations. All the possible variations are known as the “Bravais” lattices. In particular, for example, in inorganic systems, the seven different crystal systems match up with particular Bravais lattices. Table B shows the 14 Bravais lattices that are possible.
TABLE BCrystal systemBravais latticesCubicP, I, FTetragonalP, IOrthorhombicP, C, I, FMonoclinicP, CTriclinicPHexagonalPTrigonal/RhombohedralP(R)**The primitive description of the rhombohedral lattice is normally given the symbol “R”.
A variety of techniques exist for achieving crystal growth or structure in organic, inorganic, biologic, etc., systems. For example: (1) the high vacuum techniques of molecular beam epitaxy and atomic layer epitaxy cause atoms or molecules to be projected onto a surface of a substrate where the atoms or molecules become incorporated thereon (e.g., adatoms); (2) growth from solutions (e.g., epitaxial growth); (3) vapor phase growth onto one or more substrates or seed crystals; (4) growth from a liquid metal; (5) growth from a solution (e.g., aqueous, molten salts or other solvents); (6) growth from a saturated or supersaturated solution (e.g., aqueous, or other solvents); (7) growth from a melt, also known as solidification; (8) precipitation growth; (9) growth under high pressure conditions (e.g., hydrothermal); (10) chemical vapor transport reaction growth; (11) growth through electrochemical reactions (e.g., electrocrystallization); (12) growth from the solid phase (e.g., strain annealing); (13) acoustocrystallization techniques; (14) biologic techniques (e.g., sitting drop, hanging drop, containerless, etc.); and (15) numerous post-growth treatments that affect already formed structures (e.g., annealing, heat treatment, laser treatment, etching processes (e.g., chemical, thermal, etc.), etc.). Phase-diagrams are often employed to assist in understanding what potential crystalline phases or structures can be achieved by these various crystal growth, crystallization or ordering techniques and post-growth treatment techniques.
Much experimental and empirical work has been performed to determine systems and/or phases which various atoms, ions, molecules and/or macromolecules assemble into. For example, thousands and thousands of phase diagrams exist describing various organic, biologic and/or inorganic systems. Phase diagrams show equilibrium conditions for systems and exhibit, typically, the lowest known free energy states for composition, temperature, pressure and/or other conditions imposed upon the system. In particular, the traditional belief is that under a given set of fixed parameters, there will be only one mixture of phases that can be present. Phase-equilibrium diagrams provide a precise method of graphically representing equilibrium situations and are important for characterizing various organic, inorganic and/or biologic systems. The phase-equilibrium diagrams record the composition of each phase present, the number of phases present and the amounts of each phase, at equilibrium. It is noted that equilibrium conditions are rarely achieved in most systems. However, even though non-equilibrium conditions (e.g., metastable equilibrium conditions) typically prevail in real-life systems, phase-diagrams are still important to practitioners in each of their respective fields to assist in determining what phases may be present, influenced, and/or controlled, etc., in various crystallization systems.
Phase-diagrams are regularly utilized to determine phase and composition changes occurring under varying environmental conditions. For example, changes in environmental gasses present in a system, changes in partial pressures of environmental gasses, changes in temperature, changes in pressure, changes in composition, etc., are all known factors that are capable of influencing the resultant product (e.g., crystalline or structural species present) in any given crystallization reaction system.
There are numerous phase-diagrams for each of the aforementioned systems including, for example, one-component phase diagrams, two-component phase diagrams, three-component phase diagrams, etc. A good example of a single component, single-solid phase system is sodium chloride. In particular, FIG. 75 shows the relationship between temperature and pressure for the ionically bonded material known as NaCl. In addition, FIGS. 76a and 76b shown clinographic projections of the unit cell of the cubic structure for sodium chloride. FIG. 77 shows a clinographic projection of the cubic unit cell structure of sodium chloride, where the ions are shown in approximately correct relative sizes. The solid circles represent the sodium ions, whereas the hollow circles represent the chlorine ions.
Phase-diagrams can be interpreted by the phase rule (known as the Gibbs Phase Rule) which is shown in the following relationship for a single component system:P+V=C+2.
The phase rule listed above uses P for the number of phases present in equilibrium, V for the variance or number of degrees of freedom and C for the number of components. This phase rule relationship is the basis for preparing and utilizing phase-equilibrium diagrams. For example, FIG. 78 shows a perspective view of a simple binary phase-diagram. This two-component system adds an additional variable of composition to the phase rule. Thus, application of the phase rule is as follows: for the point “A” one phase is present and both temperature and composition can be arbitrarily varied. However, in areas in which two phases are present at equilibrium, the composition of each phase is indicated by lines on the diagram. The intersection of a constant-temperature line with phase boundaries gives the compositions of the phases in equilibrium at temperature “T”. Thus, with two phases present, the following phase rule relationship exists:P+V=C+2,2+V=2+2,V=2.Thus, at an arbitrarily fixed pressure, any arbitrary change in either temperature or composition of one of the phases present requires a corresponding change in the other variable. Accordingly, the maximum number of phases that can be present where pressure is arbitrarily fixed (i.e., where V=1) is as follows:P+V=C+2,P+1=2+2,P=3.
The solid horizontal line indicated by the letter C in FIG. 78, represents a situation where three phases are present and the composition of each phase and the temperature are fixed. Accordingly, phase-diagrams can be utilized to determine what phases are present, what conditions can result in certain phases being present and the compositions of certain phases.
In particular, defect crystallization pathways exist in each crystallization reaction system, and the precise crystalline pathway that is chosen is a function of many factors known to the art. For example, a representative ternary phase diagram is shown in FIG. 86a (which is representative of a ternary eutectic) and in FIG. 86b (which is representative of a ternary solid solution). Further, FIG. 86c shows one precise crystallization pathway followed by the composition “A” shown in FIG. 86a. A brief description of the crystallization pathway is as follows: a liquid having a composition A falls into a first primary field of component “X”. As the temperature in the ternary liquid is decreased to T1, a solid having a composition “X” begins to crystallize from the melt. The composition of the remaining liquid changes along the line AB due to some of the solid “X” crystallizing out therefrom. A concept known as the “lever principle” (i.e., a concept for determining relative amounts and compositions of materials which crystallize from a melt) applies along the line AB. Further, as cooling continues and the temperature reaches T2, the crystallization pathway reaches a boundary condition representing the equilibrium between the composition of the remaining liquid and the two solid phases “X” and “Z”. At this point, “Z” begins to crystallize as well as “X” and the remaining liquid changes in composition along the path CD. However, at the point “L” the phases that exist in equilibrium comprise a liquid having a composition “L”, and the solids “X” and “Z”, whereas the overall composition of the entire system is “A”. Cooling continues until a ternary eutectic occurs at TE at the point D. At the point D, composition “Y” is also capable of crystallizing.
Accordingly, various crystalline species are capable of crystallizing from, for example, the solidification of one or more species from a melt, whether the melt is under equilibrium or non-equilibrium conditions.
Another example of a phase diagram is contained in FIG. 79, which shows an example of a solubility curve. This general solubility curve is for a solid that forms a hydrate (i.e., one or more compounds that has one or more water molecules attached to it) as a system is cooled. For example, FIG. 79 could be any solid that forms hydrates such as, for example, Na2S2O3. The number of hydrate molecules shown in FIG. 79 is arbitrary and will vary for each substance.
Further, FIG. 79a shows several solubility curves for different solutes in water. Most of these materials show increased solubility as a function of temperature. Sodium chloride is one of those solutes that shows a gradually increasing solubility in water as a function of increasing temperature. Specifically, for example, the solubility plot for NaCl shows that a saturated solution of NaCl at 20° C., will comprise about 36 grams of NaCl dissolved in 100 grams of water.
Accordingly, it should be apparent that the various bonding mechanisms for bonding together ions, atoms, molecules, macromolecules, etc., result in various possibilities for crystalline and structural configurations (e.g., the different unit cells shown in FIG. 70 and the different Bravais lattices shown in FIG. 72-74). While much work has been done to categorize different chemical configurations and/or structures, as well as many theories or explanations being set forth in an attempt to explain the mechanisms of crystallization, including the initiation of crystallization as well as secondary nucleation or growth, much remains unknown regarding the ability to control various crystalline structures within, for example, one or more given species. However, it is clear that various reactions, including various bonding and chemical reactions, are important in determining certain crystalline structures.
In this regard, chemical reactions are driven by energy. The energy comes in many different forms including chemical, thermal, mechanical, acoustic, and electromagnetic. Various features of each type of energy are thought to contribute in different ways to the driving of chemical reactions. Irrespective of the type of energy involved, chemical reactions are undeniably and inextricably intertwined with the transfer and combination of energy. An understanding of energy is, therefore, vital to an understanding of chemical reactions and hence, certain structural transformations.
A chemical reaction can be controlled and/or directed either by the addition of energy to the reaction medium in the form of thermal, mechanical, acoustic and/or electromagnetic energy or by means of transferring energy through a physical catalyst. These methods are traditionally not that energy efficient and can produce, for example, either unwanted by-products, decomposition of required transients, and/or intermediates and/or activated complexes and/or insufficient quantities of preferred products of a reaction.
It has been generally believed that chemical reactions occur as a result of collisions between reacting molecules. In terms of the collision theory of chemical kinetics, it has been expected that the rate of a reaction is directly proportional to the number of the molecular collisions per second:rate α number of collisions/sec
This simple relationship has been used to explain the dependence of reaction rates on concentration. Additionally, with few exceptions, reaction rates have been believed to increase with increasing temperature because of increased collisions.
The dependence of the rate constant k of a reaction can be expressed by the following equation, known as the Arrhenius equation:k=Ae−Ea/RT where Ea is the activation energy of the reaction which is the minimum amount of energy required to initiate a chemical reaction, R is the gas constant, T is the absolute temperature and e is the base of the natural logarithm scale. The quantity A represents the collision rate and shows that the rate constant is directly proportional to A and, therefore, to the collision rate. Furthermore, because of the minus sign associated with the exponent Ea/RT, the rate constant decreases with increasing activation energy and increases with increasing temperature.
Normally, only a small fraction of the colliding molecules, typically the fastest-moving ones, have enough kinetic energy to exceed the activation energy, therefore, the increase in the rate constant k has been explained with the temperature increase. Since more high-energy molecules are present at a higher temperature, the rate of product formation is also greater at the higher temperature. But, with increased temperatures there are a number of problems which can be introduced into the reaction system. With thermal excitation other competing processes, such as bond rupture, may occur before the desired energy state can be reached. Also, there are a number of decomposition products which often produce fragments that are extremely reactive, but they can be so short-lived because of their thermodynamic instability, that a preferred reaction may be dampened.
Radiant or light energy is another form of energy that may be added to the reaction medium that also may have negative side effects but which may be different from (or the same as) those side effects from thermal energy. Addition of radiant energy to a system produces electronically excited molecules that are capable of undergoing chemical reactions.
A molecule in which all the electrons are in stable orbitals is said to be in the ground electronic state. These orbitals may be either bonding or non-bonding. If a photon of the proper energy collides with the molecule the photon may be absorbed and one of the electrons may be promoted to an unoccupied orbital of higher energy. Electronic excitation results in spatial redistribution of the valence electrons with concomitant changes in internuclear configurations. Since chemical reactions and bonding are controlled to a great extent by these factors, an electronically excited molecule undergoes a chemical reaction or bond transformation that may be distinctly different from those of its ground-state counterpart.
The energy of a photon is defined in terms of its frequency or wavelength,E=hν=hc/λ, where E is energy; h is Plank's constant, 6.6×10−34 J·sec; ν is the frequency of the radiation, sec−1; c is the speed of light; and λ is the wavelength of the radiation. When a photon is absorbed, all of its energy is typically imparted to the absorbing species. The primary act following absorption depends on the wavelength of the incident light. Photochemistry studies photons whose energies lie in the ultraviolet region (e.g., 100 Å-4000 Å) and in the visible region (e.g., 4000 Å-7000 Å) of the electromagnetic spectrum. Such photons are primarily a cause of electronically excited molecules.
Since the molecules are imbued with electronic energy upon absorption of light, reactions and structural transformations occur from different potential-energy surfaces from those encountered in thermally excited systems. However, there are several drawbacks of using the known techniques of photochemistry, that being, utilizing a broad band of frequencies thereby causing unwanted side reactions, undue experimentation, and poor quantum yield. The area of photocrystallization is still in its infancy and the known techniques are trial and error, empirical approaches, with no cohesive or comprehensive understanding of the underlying mechanisms. Some good examples of photochemistry are shown in the following patents.
In particular, U.S. Pat. No. 5,174,877 issued to Cooper, et al. al., (1992) discloses an apparatus for the photocatalytic treatment of liquids. In particular, it is disclosed that ultraviolet light irradiates the surface of a prepared slurry to activate the photocatalytic properties of the particles contained in the slurry. The transparency of the slurry affects, for example, absorption of radiation. Moreover, discussions of different frequencies suitable for achieving desirable photocatalytic activity are disclosed.
Further, U.S. Pat. No. 4,755,269 issued to Brumer, et al. al., (1998) discloses a photodisassociation process for disassociating various molecules in a known energy level. In particular, it is disclosed that different disassociation pathways are possible and the different pathways can be followed due to selecting different frequencies of certain electromagnetic radiation. It is further disclosed that the amplitude of electromagnetic radiation applied corresponds to amounts of product produced.
Selective excitation of different species is shown in the following three (3) patents. Specifically, U.S. Pat. No. 4,012,301 to Rich, et al. al., (1977) discloses vapor phase chemical reactions that are selectively excited by using vibrational modes corresponding to the continuously flowing reactant species. Particularly, a continuous wave laser emits radiation that is absorbed by the vibrational mode of the reactant species.
U.S. Pat. No. 5,215,634 issued to Wan, et al., (1993) discloses a process of selectively converting methane to a desired oxygenate. In particular, methane is irradiated in the presence of a catalyst with pulsed microwave radiation to convert reactants to desirable products. The physical catalyst disclosed comprises nickel and the microwave radiation is applied in the range of about 1.5 to 3.0 GHz.
U.S. Pat. No. 5,015,349 issued to Suib, et al. al., (1991) discloses a method for cracking a hydrocarbon to create cracked reaction products. It is disclosed that a stream of hydrocarbon is exposed to a microwave energy which creates a low power density microwave discharge plasma, wherein the microwave energy is adjusted to achieve desired results. A particular frequency desired of microwave energy is disclosed as being 2.45 GHz.
The art contains numerous well known crystallization and structure formations or modifications techniques (e.g., single crystal, polycrystalline, amorphous, etc.) as well as numerous well known post-processing techniques (e.g., annealing, chemical etching, laser etching, temperature conditioning, pressure conditioning, atmospheric conditioning, etc.) which also affect structure. The prior art techniques largely contain empirical results from many trial and error approaches that, in most cases, are not well understood at a basic level.
Physical catalysts are also well known in the art but the role that physical catalysts play in various reactions is also not well understood at a basic level. Specifically, a physical catalyst is typically regarded as a substance which alters the reaction rate of a chemical reaction without appearing in the end product. It is known that some reactions can be speeded up or controlled by the presence of substances which themselves appear to remain unchanged after the reaction has ended. By increasing the velocity of a desired reaction relative to unwanted reactions, the formation of a desired product can be maximized compared with unwanted by-products. Often only a trace of physical catalyst is necessary to accelerate the reaction. Also, it has been observed that some substances, which if added in trace amounts, can slow down the rate of a reaction. This looks like the reverse of catalysis, and, in fact, substances which slow down a reaction rate have been called negative catalysts or poisons. Known physical catalysts go through a cycle in which they are used and regenerated so that they can be used again and again. A physical catalyst operates by providing another path for the reaction which can have a higher reaction rate or slower rate than available in the absence of the physical catalyst. At the end of the reaction, because the physical catalyst can be recovered, it appears the physical catalyst is not involved in the reaction. But, the physical catalyst must somehow take part in the reaction, or else the rate of the reaction would not change. The catalytic act has historically been represented by five essential steps originally postulated by Ostwald around the late 1800's:
1. Diffusion to the catalytic site (reactant);
2. Bond formation at the catalytic site (reactant);
3. Reaction of the catalyst-reactant complex;
4. Bond rupture at the catalytic site (product); and
5. Diffusion away from the catalytic site (product).
The exact mechanisms of catalytic actions are unknown in the art but it is known that physical catalysts can speed up a reaction that otherwise would take place too slowly to be practical.
A well known category of catalysts are the autocatalysts. In autocatalysis, the product of a reaction functions as a catalyst, speeding the rate of formation of more product. In autocatalytic reactions, it is clear that the catalyst does take part in the reaction. Nevertheless, the exact mechanisms of autocatalytic actions are also largely unknown in the art.
Accordingly, what is needed is a better understanding of the crystal growth, crystallization, structural and/or phase change processes and mechanisms so that biological, organic, and/or inorganic processes and materials, etc., can be engineered by more precisely controlling the multitude of reaction processes that exist, as well as developing completely new reaction pathways and/or new and/or desirable reaction products (e.g., crystalline phases or species).